Ever hear this saying.......

[myxpykalix]

"Leave well enough alone".... I went to cut a tabletop for a friend. I went to the effort to go get a laser pointer and mount it to pre run the file to make sure my margins were ok.

Well everything went fine, the last file to run was the cutout file. It sent down to .75 and finished. Problem is the wood was .87 thick. I redid the cutout file to go down to .85 then rehomed it before starting.
Started the file and it dug down into the tabletop for no good reason. Man this happens more than it should. This time its not human error.


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[gabepari]

Jack, when I "accidentally" cut something shallow, instead of trying to recut on the bot, I just pull it off the table and use the lami-trim router with a flush bearing bit to finish it off.

It's more safer for the bot and the table


Gabe

[myxpykalix]

Well heres another saying...."hindsight is 20/20"

My intuition was saying, leave it alone, but i didn't listen...oh well

[ron_varela]

Jack the fix for that problem is to edit the sbp file and run file again.


Ron

[myxpykalix]

That was what i did changing the depth from .75 to .85 and i did a JH and restarted the file thinking it would just go and air cut the same path till it got down to .75 but it just went and cut what you see in the picture.

[ron_varela]

Did you re-zero your material?
When you edit a file you need to treat it as a new one, you need to re-zero your material.

Ron

[fleinbach]

Jack,

Did you manualy stop the file when it started to cut wrong?

Re-zeroing the material will have no bearing on any changes you make in a parts file.

[ron_varela]

Jack in the last 10 years and thousands of hours of machine time I never had a bit go deeper then it was programmed to do.
When I needed it to go deeper I send the machine home and edit the file to the new depth, then I would re-zero and run the file again.
A good rule of thumb is if it worked the first time do everything the same the 2nd time.
There are other ways to fix the same problem but my way of thinking is this, I would rather spend the extra few seconds to re-zero then to have to spend the $$$$ to buy new material or to tell the customer I made a mistake.

Ron

[fleinbach]

Ron,

I didn't mean to say that re-zeroing isn't a good practice particularly when somrthing goes wrong. I was only trying to point out that an error after changes are made to a parts file do not mean the tool lost it's position. Most likely there was an error in the changes made to the file. It is easy to make an error when changing a cut file. Even if you know exactly what change you need to make there is still the potential to make a type "o" and not pick it up. I just made 2 while typing this sentance but caught them and made the corrections.

When I worked for the telephone company in cable repair there was a standard ticket we filled out. One of the check boxes was for employee caused trouble. According to the feedback we recieved 90 percent of all troubles where employee caused errors. People make mistakes.

When changing a parts file it is very easy to make a mistake. I have done it myself.

In 4 years I have never noticed a bit go any deeper than it was programmed to go but I have erroneously meant to type .3 but missed the decimal and watched the collet try to go through the material.

When possible instead of changing the prts file if it is just a cutout routine I

[myxpykalix]

Maybe i mis-stated the error. I set the file up to cut the 2 outside rings as one file, no problem. I set the inside star pattern as another cutting file, no problem. I set up the cutout file to cut it from material at .75 deep. Every file worked fine and it went back to home position and I stopped router. I moved carriage out of the way (with the arrow button on console) to inspect cut. I took calipers and realized it was 13-14 thousandths still left in outside ring cut and it hadn't gone thru.

So i did a JH to get it back to center home. I redid the cutout file setting the depth from .75 to .85. renamed the file to a new name. Called it up to start. It went and did exactly what you see. I might understand if i had any changes like moved material or lost settings or had interrupted the file earlier but none of that happened. This isn't the first time this has happened. I'm going to turn the material over and see if i can rescue it my redoing it on the opposite side.

[harryball]

Jack... if you are seeing "return to home" errors on a regular basis, i.e. 0,0 ends up being random on JH then something is amiss and before I did anymore work I would solve it.

Try testing the bot and looking for a pattern. Use your laser pointer and mark 0,0 so you know when you are on top of it. Then try jogging about at 25 ips (I'm assuming you have an alpha) and returning to home. You can try moves under load (push on the gantry opposing it's motion) as if it is cutting or actually cut something... but you should ALWAYS JH to 0,0 unless you loose steps or have a mechanical issue.

I had a similar problem right after I got my bot and that's basically what I did with a V bit. I learned I was always off in the Y direction but never the X. I finally figured out that the spring on the Y motor was not tightned and I was walking over the rack at times. Not a big deal, solved it myself and didn't even need to ask the forum (I was proud of myself).

We all do dumb things (I'd refer you to my stuck to the bot thread) and tools malfunction. We need to remember even if it is the tools fault... it's not the tools fault. In your case... I really think you should expend all your energy figuring out why your bot looses position before figuring out how to rescue the work piece.

Just my 2 cents.

Robert

[myxpykalix]

No Harry this wasn't a case of losing its home position. After it finished all of the cutting it went right back to home position. I moved the carriage manually (via console)to inspect the cut then moved it back to home via JH and it was exactly where it needed to be. Only after it started on the revised part file is where it had its screwup.

And the only modification to that file was the depth setting. And my thought was, lets say it lost its home position and wanted to cut the outside cutout say from a differnt home position it would have cut in the pattern of the outside cut but it just moved over and cut in that jagged pattern you see there. Thats why i don't think it is a matter of losing "home position".

So boys and girls what have we learned from this?....."Leave well enough alone"!!!

[myxpykalix]

I'll end this with one last saying I think goes like this "snatching victory from the jaws of defeat"...well i turned jig and piece over measured to find center, set it so i knew that the piece was straight in the X and Y axis regardless of how the jig sat on the table and redid the file. I admit that I am off by 1/32th" but thats good enough for me. Pretty good for doing it by eye. I think more than anything it was just plain LUCK.


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